In the field of sprung balance resonators, the main defect of the compensating alloys for a current iron-nickel or iron-cobalt based balance spring is their sensitivity to magnetic fields. Thus, a watch which is set perfectly in the absence of a magnetic field may gain or lose several tens of seconds after having been subjected to the influence of an external magnetic field. We are increasingly subject to magnetic radiation in our daily lives.
To overcome these drawbacks, alternative balance springs have been developed based on paramagnetic materials comprising, for example, niobium, or diamagnetic based materials including, for example, silicon. However, these balance springs are very difficult to develop and, incidentally, expensive to produce compared to current iron-nickel or iron-cobalt based balance springs.